Not wanting to muddy the waters with even more possibilities, but decided to do what Mark did and look through my old log files and came across the same 01119 error code in both scans of April 2017 and 2018 (before the MOT).

However, I've never had the big red exclamation mark appear (except when doing a scan with VCDS, but with the same flashes/beep sequence), but have had both yellow warning lights come on and stay on. That's usually accompanied by error code 18265 appearing both in the ABS and Transmission modules, and can only be cleared with VCDS.

It won't but, as I said, sounds like 2 problems. Fix 1, work forwards. ;)

Low fluid would have been my guess too....

It might be above minimum, but if you set off in a rapid enough fashion, the fluid could slosh back and register low. I've definitely had this on a D2 S8 before.

I'd definitely top it up, as there's no harm in doing that, and it could help further diagnose that issue....

I concur that the low brake fluid warning is completely independent of the gear recognition code.....

+++
Thanks for all the suggestions and advice. So, first thing is to top up the brake fluid and, secondly, do a re-scan after taking it for a spirited drive.

Well, the brake fluid level does seem to be the cause. Took it out today to pick up some brake fluid and going around a roundabout without acceleration it alarmed. Topped up the system and then took it out again - no alarms despite some hard acceleration/maneuvering +++
As the photo shows the level is not that low but I believe the sensor is at the front on the low level line so acceleration will cause an alarm.
Check scanned and cleared the DTCs so will take it out again after the rugby today and check what happens to the 01119 Gear Recognition signal....

Thanks for the suggestions guys.

Huzzah! Hopefully the 01119 code is just from using Tiptronic like some cars seem to do.

Worth checking the state of your brake pads with the fluid that low - it has to have gone somewhere +++

Yes indeed, that was the next thing worrying me! Both front rear calipers have been refurbed in the last couple of years and the pads replaced within the last two years and my mileage is pretty low these days.

Is this still occurring?
I would suspect MAF in this case.
Any rough shifting, particularly at WOT?

Car has been off the road and under wraps since May 2018, as the plan was to fix it up and keep it long term. Current daily is an '04 A8.

Had to Google WOT first, but don't drive the car like that. More of a 'Driving Miss Daisy' driver. I do have the odd hiccup with the gearbox, and the F125 switch is on my list of purchases.

Watching with interest as I get the same issue intermittently. Cured by a restart but oddly always seems to require I remove the key